Asphalt has long been employed in modern society for tasks such as road construction and/or repair. Generally speaking, asphalt pavement is comprised of a mixture of petroleum-based bitumen and a filler such as aggregate. The petroleum-based bitumen is obtained, for example, from petroleum processing plants since bitumen is one of the remaining heavy by-products of the petroleum processing process.
At room temperature, asphalt is formulated to remain in its solid state to provide the desirable mechanical characteristics for construction purposes. To facilitate application of asphalt to the work surface, the asphalt is rendered more flowable by either heating or emulsification. In heating, the asphalt mixture that includes the bitumen as well as any optional filler is heated above the mixture's melting point. For example, at above a few hundred degrees (Fahrenheit), the mixture becomes more fluid-like and can be more easily applied.
In emulsifying, the bitumen material is sheared or broken into tiny particles and then mixed with a soap solution and water. The tiny bitumen-based particles are kept in suspension until applied. During the curing process, the soap and water are drawn from the applied mixture, allowing the particles of petroleum-based bitumen to bind to one another or to an aggregate, thereby forming the desired resultant construction asphalt.
To further elaborate on the emulsification process, base asphalt is typically provided from a petroleum processing plant. The base asphalt is first heated up to, for example, 350 degrees and then injected into a colloid mill for mixing with a soap mixture. Inside a colloid mill, the hot base asphalt is sheared or broken up into fine particles of roughly 3-10 microns in size or smaller. The fine particles of the base asphalt are then mixed with a soap solution and water to create an asphalt emulsion. The resultant asphalt emulsion may then be stored for future use or immediately applied to the work surface, either by itself or mixed with some other filler. Other materials such as a set retarder (to control the set time) or one or more compounds to improve certain characteristics of the resultant asphalt may also be added.
In practice, it is often a challenge to reliably create a stable, long-shelf life asphalt emulsion. This is due to a variety of factors. For example, different base asphalt materials (e.g., from different types of crude oil) may react differently to the same emulsification formula and/or soap mixture. In other example, different handling arrangements (e.g., pumps) may cause a particular batch of asphalt emulsion to fail but not another. In other examples, differences in the ambient temperature during storage may affect the resultant asphalt emulsion. In some cases, the asphalt particles may refuse to stay in suspension, resulting in a failed batch. In other cases, the resultant asphalt emulsion may have less than desirable mechanical or temperature-dependent properties, which affect the durability of the work product. In still other cases, the resultant asphalt emulsion may have an undesirably short shelf-life.
Creating an improved asphalt emulsion is one of the goals of the present patent application.